Air Bubble Characters Float Along This Unique Scrolling Display

We’ve seen a lot of unique large-format scrolling message boards on these pages, but most of them use some sort of established technology – LEDs, electromechanical flip-dots, and the like – in new and unusual ways. We’re pretty sure this air-bubble dot matrix display is a first, though.

While it may not be destined for the front of a bus or a train station arrivals and departures board, [jellmeister]’s bubble display shows some pretty creative thinking. It started with a scrap of multiwall polycarbonate roofing – Corotherm is the brand name – of the type to glaze greenhouses and other structures. The parallel tubes are perfect for the display, although individual tubes could certainly be substituted. A plastic end cap was fabricated; air nozzles in each channel were plumbed to an air supply through solenoid valves. An Arduino with a couple of motor driver hats allows pulses of air into each channel to create reasonably legible characters that float up the tube. The video below shows it in use at a Maker Faire, where visitors could bubble up their own messages.

It took some tweaking to get it looking as good as it does, but there’s plenty of room for improvement. We wonder whether colored liquid might help, or perhaps adding a Neopixel or even a laser to each channel to add some contrast. Maybe something to cloud the water slightly would help; increasing the surface tension with a salt solution might make the bubbles more distinct. We doubt it’ll ever have the contrast ratio of a flip-dot display, but it certainly has a charm all its own.

16 thoughts on “Air Bubble Characters Float Along This Unique Scrolling Display

  1. For more bubble-fun, take a look at Bruce Shapiro’s Pipedream series.

    Some of us helped him build a 96-tube one in the Ontario Science Centre.

    It was super fun getting a pair of 300 MHz fanless/no hard-drive ttylinux machines connected by WifFi to do the image processing. (64 megabyte CFlash for nonvolatile storage.)

    1. Excellent gallery, thanks for sharing! Super cool project. With modern microcontrollers and single board linux computers being what they are, wonder if this would be an easier feat to do today as opposed to when you guys did it? The physical side seems to have been quite the undertaking though, and that wouldn’t change much.

  2. Hi,
    Jellmeister, creator of this particular display here.

    I knew it wasn’t the first, but please lay off Dan about the whole ‘first’ thing. Yes it’s unfortunate, and it is always easy to criticise, but the research is as good as newspaper articles you actually pay for, and remember that the longer writers spend researching each piece the fewer interesting articles people get to see. While a lot of people have seen a bubble display, a lot more haven’t so, novel or not, I hope this is still interesting.
    It’s facinating to see all the other displays, older, bigger, better. So thanks for sharing links.

    I hadn’t seen one when I conceived the idea, but when mine was still an idea and a box of parts I went to a trade show where a valve manufacturer had made a huge and very nicely made one. I built this with Mark, the other half of Jelly and Marshmallows, with a very low budget and short timescales, so I only had the 12 valves that had been chucked out at work, so was never going to compete with the big ones. I did think this is quite a nice project for someone with time to wait for a batch of valves from China, as it is totally scalable. I have shared instructions and my code on the linked Instructables if anyone wants to replicate it.

    1. I strongly agree. Accusations of a crime or reports of that sort are held to one standard, but a cheerful ‘Feels new!’ should be held to a much lighter standard.

      Although if we conveniently have one of the team on hand here I do have a question: Why that particular angle for the display? I notice all the other displays went vertical. I’m guessing this leaves the letters up for more time? But is that perhaps making them less stable? And is that a trade off that varies across angles?

      1. If you only have 12 valves, and no budget for more/time for China to deliver, you are limited to scrolling the text horizontally like an LED display. This is much easier to read if it is broadly the right way up. The rise time isn’t that different from vertical (factor of 2?), and I’d like it faster anyway as it takes forever to say anything! Rising stability was an issue, but it is almost entirely related to pulses from subsequent bubbles disturbing the flow. Bubble size is also affected by preceding bubbles (or more the inertia of the stretch of water before the first compressible bubble), and given tight project timescales I didn’t have time to vary valve times to compensate.

  3. Now I wonder about those glycerin lamps – the ones where monofilament fishing line allows glycerine drops to fall, mimicking rainfall and whether some droplet dispenser could be used to make similar displays. Unlike bubbles, later drops of glycerine would not seem to interfere with drops already in motion. The drops are necessarily smaller so either a tiny display or one with greater detail.

  4. I imagine the display is at an angle to slow the rise of the bubble to make it more visible. Perhaps could achieve the same effect with a more viscous fluid. Or bubbles of colored oil? And the inverse might be neat: bubbles of colored water in a tank of oil dropping.

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